1. Field
Aspects of embodiments of the present invention relate to a web thickness measuring equipment and a method of measuring a web thickness.
2. Description of the Related Art
As development and demand for mobile techniques has recently increased, demand for a rechargeable battery as an energy source is rapidly increasing. Accordingly, research into batteries satisfying various requirements is underway. Particularly, a lithium secondary battery that has high energy density, discharge voltage, and output stability is increasingly demanded.
In general, a secondary battery is manufactured by forming each of a positive electrode plate and a negative electrode plate (referred to herein as a positive web and a negative web) by coating an active material on a current collector, interposing a separator between the positive and negative webs to form an electrode assembly, mounting the electrode assembly in a prismatic metal can or a pouch-type case formed of an aluminum laminate sheet, and injecting or impregnating a liquid electrolyte into the electrode assembly or using a solid electrolyte.
In the manufacture of secondary batteries, it is important to manufacture as many batteries as possible while maintaining the same quality. Accordingly, it is important to reliably manage a thickness of a web formed with a current collector.
Conventionally, in manufacturing a web of a secondary battery, optical equipment is installed around the web wound on a roll and an image of the web is acquired from the optical equipment, thereby measuring the thickness of the web.
However, in the conventional web thickness measuring equipment, continuous use of a roll may result in deformation of the roll, and an error in measuring the thickness of the web may be generated. In addition, in view of characteristics of the web of the secondary battery, web thickness measurement may not be properly performed due to the pattern formed on the web wound on the roll.